Battery-operated power tools, such as cordless screwdrivers, are conventional. During operation, they may be heavily loaded by widely fluctuating loads and load changes—when a hole saw gets stuck, for example—so that mechanical components of the power tool usually have a reduced operating life. A spontaneous increase in load torque may furthermore cause components to fail or produce spontaneous changes in the holding force for an operator or user.
To avoid this, either high-strength components or components of larger dimensions, which, however, are more expensive, bigger and/or heavier, are typically used for mechanical components in battery-operated power tools.
A battery-operated power tool is described in U.S. Published Patent Application No. 2009/0065225 A1, the power tool having an electric motor. An electric motor current is monitored, and a change over time in the motor current is measured. If this measured value exceeds a predetermined value, the drive motor is stopped.
One disadvantage of the conventional power tools is, in particular, that a corresponding stopping device which stops the drive motor remains active so that further operation of the power tool is possible only after active acknowledgement of the shutdown by a user. This means, in particular, that a user must manually deactivate or reset the stopping device.